1. Field of the Invention
The present invention relates to a rolling contact bearing assembly utilizing a plurality of rollers and a cage, or a roller bearing, and, more particularly, to an improvement of the cage designed to avoid the occurrence of fretting and generation of obnoxious noises during the operation of the roller bearing.
2. Description of Related Art
It is well known in the art that a cage equipped needle roller bearing is currently largely employed not only in automotive vehicles, but also in various industrial machines and equipments because it has light weight and compact features. For example, a transmission for use in an automotive vehicle makes use of the cage equipped needle roller bearing as an idler bearing. The cage equipped needle roller bearing is currently available in two types, one piece type and split type, and the split type is generally considered desirable particularly where prevention of fretting in bearing is of a prime concern.
More specifically, in the idler bearing of the kind referred to above, when speed change gears are engaged with each other, the speed change gear rotates together with a shaft and therefore, a relative rotation of the bearing becomes zero. For this reason, each of rollers tends to be loaded with a load always at the same circumferential position as an inner diametric surface of the gear and an outer diametric surface of the shaft, both of which define a raceway surface, accompanied by a faint quivering, which eventually leads to a wear. This wear in turn leads to formation of wavy dents at a pitch equal to the pitch of the rollers over the entire periphery of the raceway surface, accompanied by generation of a fretting wear.
If a cage is employed in the form of the split type cage, a relative rotation occurs in cage halves in a non-loaded condition in the presence of a circumferential gap left by the split, and as a result, the fretting can be prevented.
However, regarding the bearing of the type in which the cage is of the split type as hereinabove discussed, the two cage halves are required to be assembled separately even though they can be assembled in an axial direction. In addition, after the cage has been assembled on the shaft during the assembling work, there is the inconvenience that at the time of assemblage of, for example, the speed change gears, the cage may fall unless it is manually retained or fixed by a jig, and, hence, the work efficiency is worse. Also, the two cage halves are separate from each other, the number of component part is indeed many and, therefore, there is a problem in respect of storage and transportation.
In an attempt to alleviate the foregoing problems and inconveniences, the following suggestions have been made in the art concerned.
(1) The cage is split into a pair of cage halves, which are in turn bonded together by means of a bonding agent applied to circumferential ends of those cage halves, so that the bonding agent can be fused by the temperature then increasing as a result of the operation. In this respect, see the patent document 1 listed below.(2) The cage is split into a pair of cage halves, which are in turn temporarily connected together by means of a temporary joint member applied to circumferential ends of those cage halves. Material used for the temporary joint member has an affinity to a lubricant oil and is rendered to be a soluble resin. In this respect, see the patent document 2 listed below.(3) The cage is split into, for example, a pair of cage halves, which are in turn temporarily connected with each other at respective ends of the cage halves by means of a weld, so that temporarily connected portions may be destructed by stresses during the operation. In this respect, see the patent document 3 listed below.(4) The case is split into, for example, a pair of cage halves, which are in turn connected together in a fashion displaced axially relatively, so that during the assemblage a pressing force is applied to remove the axial displacement thereof. In this respect, see the patent document 4 listed below.